JP4680515B2 - Nanocrystalline zeolite particles and production method thereof - Google Patents

Description

  The present invention relates to highly uniform nano-sized zeolite particles having a particle size that is close to the average particle size, which is useful in catalysts, adsorbents, ion exchangers, optical materials, film formation, and the like, and a method for producing the same. It is.

  It is generally well known that nano-sized zeolite having a uniform particle size is useful when zeolite is used in a catalyst, an adsorbent, an ion exchanger, a membrane, an optical material, a membrane formation, and the like. There are some reports on nano-sized zeolite with uniform particle size.

  For example, Patent Document 1 discloses a colloidal zeolite having an average particle size of less than 200 nm and a geometric standard deviation of particle size distribution of less than 1.30. In the example of Patent Document 1, a mixture of A-type zeolite and Y-type zeolite having an average particle size of 100 nm and a geometric standard deviation of the particle size distribution of 1.11 has been reported.

  Patent Document 2 discloses a molecular sieve having an average maximum dimension of 100 nm or less and a dispersion of the maximum dimension being less than 15% of the average longest dimension. However, in that example, no specific maximum dimension dispersion has been reported.

  Further, Patent Document 3 discloses an A-type zeolite having an average primary particle size of 0.1 μm or less and a coefficient of variation of the primary particle size of 60% or less. In that example, a particle A type zeolite having an average primary particle size of 0.03 μm (coefficient of variation: 15%) has been reported.

However, for use in catalysts, adsorbents, ion exchangers, membranes, optical materials, membrane formation, etc., the particle size uniformity of conventional nanosize zeolite is still insufficient, and further improvement in uniformity is desired. It was rare. In particular, in order to improve various performances, there has been a demand for nano-size zeolite having a large particle size with more particles near the average particle size.
Japanese National Patent Publication No. 8-500574 Japanese Patent No. 3417944 JP 2003-146649 A

  The problem to be solved by the present invention is that nanosized zeolite particles having a large number of particles in the vicinity of the average particle diameter are useful for catalysts, adsorbents, ion exchangers, optical materials, film formation, etc. It is to provide.

  As a result of intensive studies on the synthesis conditions of nano-sized zeolite particles, the present inventors have found that a mixed solution of a surfactant and an organic solvent contains Si or Si and Al zeolite constituents and quaternary alkylamine hydroxylation. By adding an aqueous solution containing a composite sol composed of a product to prepare a microemulsion solution or emulsion solution composed of an aqueous phase, an oil phase and a surfactant, and forming zeolite particles by hydrothermal treatment at 50 ° C. to 200 ° C., It has been found that an average particle diameter D composed of crystalline silica or crystalline aluminosilicate is 50 nm to 200 nm, and zeolite particles in which 80% or more of the particles are distributed in the range of 0.9D to 1.1D can be produced, The present invention has been reached.

  The zeolite particles of the present invention are particles in which the average particle diameter D made of crystalline silica or crystalline aluminosilicate is 50 nm to 200 nm, and 80% or more of the particles are distributed in the range of 0.9D to 1.1D. It is.

  The zeolite of the present invention is a nano-sized zeolite having a high particle size uniformity with more particles in the vicinity of the average particle size.

  By the method of the present invention, it is possible to easily adjust a nanosize zeolite having a larger particle size and having more particles near the average particle size.

  The best mode for carrying out the present invention will be described below.

In the present invention, the zeolite structure is MFI, FAU or MOR structure . Among these structures, MFI type structures that are particularly useful for catalysts, adsorbents, ion exchangers, optical materials, film formation, etc. are preferred. Also, the molar ratio of silica / alumina in the zeolite is not limited (silica / alumina ratio = 2 to ∞ (if it is ∞, it is a crystalline silica)). Furthermore, ion species are not limited, and H, NH ₄ , Na, K, Mg, Ca, Fe, Co, Ni, Cu, Zn, Ag, and the like can be exemplified.

  The particle diameter in the present invention refers to the primary particle diameter and can be measured with a scanning electron microscope, a transmission electron microscope, or the like. When the primary particles of zeolite can be approximated to a sphere, the diameter is the primary particle diameter. When it is difficult to approximate the sphere, the average of the major axis diameter and the minor axis diameter is taken as the primary particle diameter. As the average particle size, the average particle size based on the number average is used.

  The average particle size D of the zeolite of the present invention is essential to be 50 nm to 200 nm. When the average particle diameter D is less than 50 nm, the performance is strongly influenced by the outer surface of the zeolite, and various performances in the catalyst, adsorbent, ion exchanger, optical material, film formation, etc. are lowered, and the stability of the zeolite structure is also lowered. Therefore, it is not preferable. On the other hand, when the average particle diameter D exceeds 200 nm, for example, the influence of diffusion in the zeolite crystal in the catalyst becomes large, and the selectivity of the reaction is lowered, so that various performances are lowered.

  As an index representing the uniformity of the particle diameter, the dispersion, coefficient of variation, etc. are values obtained on the assumption that the particle diameter distribution is a normal distribution. Therefore, in the present invention, the index is more realistic. The proportion of particles distributed in the range of 0.9D to 1.1D is used. The ratio of particles is calculated based on the number.

  In the zeolite of the present invention, it is essential that 80% or more of the particles are distributed in the range of 0.9D to 1.1D. When it is lower than 80%, various performances are lowered in use in catalysts, adsorbents, ion exchangers, optical materials, film formation, and the like. If it is 80% or more, the larger one is preferable, and 90% or more is particularly preferable.

  The zeolite of the present invention is obtained by mixing an aqueous solution containing a composite sol composed of a zeolitic component of Si or Si and Al and a quaternary alkylamine hydroxide into a mixed solution of a surfactant and an organic solvent. And a microemulsion solution or emulsion solution comprising an oil phase and a surfactant, and can be produced by forming zeolite particles by hydrothermal treatment at 50 ° C. to 200 ° C.

  In the mixed solution of the surfactant and the organic solvent, the type of the surfactant is not limited, but a nonionic surfactant is preferable. In particular, polyoxyethylene cetyl ether, polyoxyethylene nonylphenyl ether, and polyoxyethylene oleyl ether are preferable. Further, in the polyoxyethylene group, the average added mole number of the oxyethylene is preferably 5 to 30, and most preferably 5 to 20. The type of the organic solvent is not limited, but non-hydrophilic solvents such as cyclohexane, cyclohexene, and normal hexane are preferable. The surfactant concentration in the organic solvent is not particularly limited, but is preferably 0.1 mol / l to 1 mol / l, and particularly preferably 0.3 mol / l to 0.5 mol / l.

It is essential that the raw material of the zeolite particles of the present invention is an aqueous solution containing a composite sol composed of Si or Si and Al zeolite constituents and a quaternary alkylamine hydroxide. The aqueous solution containing the composite sol may contain other components exemplified by Na, K, NH ₄ , Cl, Br, and NO ₃ .

  In an aqueous solution containing a composite sol composed of Si or Si and Al zeolite constituents and a quaternary alkylamine hydroxide, examples of the Si source include silicon alkoxide and sodium silicate. Furthermore, when producing zeolite containing Al, examples of the alumina source include aluminum alkoxide and aluminum nitrate. The concentration of Si in the aqueous solution is preferably 0.3 mol / l to 2 mol / l, more preferably 0.5 mol / l to 1 mol / l. The concentration of Al is preferably 0 to 0.2 mol / l, and more preferably 0 to 0.1 mol / l. As the raw material alkoxide, an alkoxide having a lower alkyl group having 1 to 6, preferably 1 to 3 carbon atoms can be used.

  When the carbon number of the alkyl group chain of the quaternary alkylamine hydroxide is 1 (tetramethylammonium hydroxide), the zeolite of FAU structure, when the alkyl group chain has 2 carbon atoms (tetraethylammonium hydroxide) Can be produced mainly with zeolite of MOR structure, and when the alkyl group chain has 3 carbon atoms (tetrapropylammonium hydroxide), silicalite and zeolite with MFI structure represented by ZSM-5 can be mainly produced. The concentration of the quaternary alkylammonium hydroxide can be exemplified by 0.2 mol / l to 0.5 mol / l, preferably 0.3 mol / l to 0.4 mol / l.

  A composite sol consisting of Si or Si and Al zeolite constituents and a quaternary alkyl ammonium hydroxide may be aged after mixing and then crystallizing to form zeolite crystal nuclei. preferable. As aging conditions, it is preferable to hold at a temperature lower than the crystallization temperature for 1 hour or more.

  The amount of the aqueous solution containing a composite sol composed of Si or Si and Al zeolite constituents and quaternary alkyl ammonium hydroxide added to the mixed solution of the surfactant and the organic solvent is the mixed solution 1 of the surfactant and the organic solvent. 50 to 1500 cc per liter, preferably 80 to 100 cc.

  A method for mixing a mixed solution of a surfactant and an organic solvent and an aqueous solution containing a composite sol composed of a zeolitic component of Si or Si and Al and a quaternary alkylamine hydroxide is not particularly limited. It is preferable to add dropwise an aqueous solution containing a composite sol composed of a zeolitic component of Si or Si and Al and a quaternary alkylamine hydroxide to a mixed solution of an organic solvent and Si.

  The microemulsion solution or emulsion solution produced by mixing is preferably further stirred at high speed. In some cases, a salt such as sodium chloride or potassium chloride may be added to the microemulsion solution or emulsion solution for the purpose of controlling the type and amount of ions contained in the zeolite.

  Next, the microemulsion solution or emulsion solution is crystallized by holding at 50 to 200 ° C., preferably 80 to 160 ° C. for 2 to 60 hours, preferably 10 to 48 hours. . Under hydrothermal conditions, it is preferable to stir at high speed.

  The zeolite particles are obtained by filtering from the liquid after completion of crystallization and then washing with an organic solvent such as ethanol and / or water. Further, after drying, the quaternary alkylammonium hydroxide and the adhering surfactant can be removed by baking at 300 to 700 ° C., preferably 400 to 600 ° C. in a stream of nitrogen and / or air. it can.

  Zeolite may be chemically modified by ion exchange, ion loading, or the like, and in some cases, it may be formed into a granular or membrane shape and used as a catalyst, an adsorbent, an ion exchange agent, an optical material, or the like.

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the examples.

(Manufacture of silicalite (MFI type zeolite) particles)
70 ml of 0.5 mol / l surfactant polyoxyethylene (average addition mole number 15) cetyl ether-cyclohexane solution is put into a beaker with an internal volume of 100 ml to prepare a mixed solution of a surfactant and an organic solvent. did. Next, 35 cc of 50 cc of ion-exchanged water and 10 wt% concentration of tetrapropylammonium hydroxide aqueous solution were added to a beaker having an internal volume of 100 ml. 15 g of ethyl silicate is added to the solution, and the mixture is stirred at room temperature for 24 hours to age a zeolite precursor that is a constituent of Si zeolite, and a composite sol with tetrapropylammonium hydroxide that is a quaternary alkylamine hydroxide. Was generated. 10 cc of the aqueous solution containing the composite sol was added to the mixed solution of the surfactant and the organic solvent, and the mixture was stirred with a magnetic stirrer at 50 ° C. to prepare a microemulsion. The microemulsion solution is stirred well for 1 hour and transferred to an autoclave having an internal volume of 100 cc. Thereafter, hydrothermal synthesis was carried out at 80 ° C., 100 ° C., 120 ° C., 140 ° C., and 160 ° C. with stirring to produce MFI type silicalite particles.

  After hydrothermal synthesis, the produced precipitate was immediately recovered from the mother liquor. The obtained precipitate was washed three times with propanol to sufficiently remove the surfactant and organic solvent contained in the precipitate. This precipitate was dried at 80 ° C. for 12 hours, and then calcined at 500 ° C. for 5 hours under air flow. As a result, about 1.0 g of MFI type silicalite particles were obtained. 100 or more primary particle diameters (the average of the major axis diameter and the minor axis diameter was determined as the primary particle diameter) of the particles thus obtained were determined using a scanning electron microscope. The proportion of particles in the range 9D to 1.1D was determined. The results are shown in Table 1. The resulting particles were nanoscale and uniform MFI type silicalite particles.

(Manufacture of silicalite (MFI type zeolite) particles)
In Example 1, it manufactured similarly except having used polyoxyethylene (average addition mole number 15) oleyl ether for surfactant.

  In this case, the obtained particles were MFI type zeolite particles, and the particle size was nanoscale and uniform MFI type silicalite particles. Table 2 shows the characteristics (calculated in the same manner as in Example 1) of these MFI type silicalite particles.

(Manufacture of silicalite (MFI type zeolite) particles)
In Example 1, an experiment was conducted in the same manner except that polyoxyethylene (average number of moles of added 5) nonylphenyl ether was used as the surfactant. At this time, the surfactant / organic solvent / zeolite precursor aqueous solution was in a cloudy emulsion state.

  In this case, the obtained particles were MFI type zeolite particles, and the particle size was nanoscale and uniform MFI type silicalite particles. The characteristics (calculated in the same manner as in Example 1) of these MFI type silicalite particles are shown in Table 3, and a scanning electron micrograph is shown in FIG.

(Production of ZSM-5 (MFI type zeolite) particles)
70 ml of 0.5 mol / l surfactant polyoxyethylene (average addition mole number 15) oleyl ether-cyclohexane solution is put into a beaker with an internal volume of 100 ml to prepare a mixed solution of a surfactant and an organic solvent. did. Next, 35 cc of 50 cc of ion exchange water and 10 wt% concentration of tetrapropylammonium hydroxide aqueous solution are added to a beaker having an internal volume of 100 ml. 10 g of ethyl silicate is added to the solution and stirred at room temperature for 1 hour. Further, 0.6 g of aluminum alkoxide (aluminum triisopropoxide) was added to the aqueous solution, and the mixture was stirred at room temperature for 24 hours to age the zeolite precursor, which is a zeolite constituent of Si and Al, to form a quaternary alkylamine hydroxide. A composite sol with some tetrapropylammonium hydroxide was produced (silica / alumina molar ratio of the zeolite precursor was about 60). 10 cc of the aqueous solution containing the composite sol was added to the mixed solution of the surfactant and the organic solvent, and the mixture was stirred with a magnetic stirrer at 50 ° C. to prepare a microemulsion. The microemulsion solution is stirred well for 1 hour, transferred to an autoclave with an internal volume of 100 cc, and then hydrothermally synthesized at each temperature of 100 ° C., 120 ° C., 140 ° C., and 160 ° C. with stirring to produce MFI. Type zeolite particles were produced.

  Washing, drying, and firing after hydrothermal synthesis were in accordance with Example 1. Thereafter, the obtained particles were dispersed in a 1 mol / l ammonium nitrate aqueous solution, subjected to ion exchange treatment, sodium ions in the zeolite were removed, dried again at 80 ° C., and calcined at 500 ° C.

  The particles thus obtained were MFI type zeolite particles having a uniform particle size and a solid acidity. Table 4 shows the characteristics (calculated in the same manner as in Example 1) of these MFI-type zeolite particles.

(Manufacture of Y-type zeolite particles)
70 ml of 0.5 mol / l surfactant polyoxyethylene (average addition mole number 15) oleyl ether-cyclohexane solution is put into a beaker with an internal volume of 100 ml to prepare a mixed solution of a surfactant and an organic solvent. did. Next, 7.0 g of 50 cc of ion exchange water and 10% concentration of tetramethylammonium hydroxide aqueous solution are added to a beaker having an internal volume of 100 ml. 10 g of ethyl silicate is added to the solution and stirred at room temperature for 1 hour. Further, 2.0 g of aluminum alkoxide (aluminum triisopropoxide) was added to the aqueous solution, and the mixture was stirred at room temperature for 24 hours to age the zeolite precursor, which is a zeolite constituent of Si and Al, to form a quaternary alkylamine hydroxide. A composite sol with some tetramethylammonium was produced (the zeolite precursor has a silica / alumina molar ratio of about 10). 10 cc of the aqueous solution containing the composite sol was added to the mixed solution of the surfactant and the organic solvent, and the mixture was stirred with a magnetic stirrer at 50 ° C. to prepare a microemulsion. This microemulsion solution is stirred well for 1 hour, transferred to an autoclave with an internal volume of 100 cc, and hydrothermal synthesis is carried out at 100 ° C, 120 ° C, and 140 ° C under stirring to produce Y-type zeolite particles. Went.

  Washing, drying, and firing after hydrothermal synthesis were in accordance with Example 1. Thereafter, the obtained particles were dispersed in a 1 mol / l ammonium nitrate aqueous solution, subjected to ion exchange treatment, sodium ions in the zeolite were removed, dried again at 80 ° C., and calcined at 500 ° C.

  The particles thus obtained were Y-type zeolite particles having a uniform particle size and a solid acidity. Table 5 shows the characteristics (calculated in the same manner as in Example 1) of these Y-type zeolite particles.

(Manufacture of mordenite type zeolite particles)
A beaker with an internal volume of 100 ml was charged with 70 cc of a 0.5 mol / l surfactant polyoxyethylene (average addition mole number 15) oleyl ether-cyclohexane solution to prepare a mixed solution of a surfactant and an organic solvent. . Next, 50 cc of ion exchange water and 80 cc of 10% strength tetraethylammonium hydroxide aqueous solution were added to a beaker having an internal volume of 100 ml. 10 g of ethyl silicate was added to the solution and stirred at room temperature for 1 hour. Further, 1.0 g of aluminum alkoxide (aluminum triisopropoxide) was added to the aqueous solution, and the mixture was stirred at room temperature for 24 hours to age the zeolite precursor which is a zeolite constituent of Si and Al, and a quaternary alkylamine hydroxide. A composite sol with some tetraethylammonium hydroxide was produced (the silica / alumina molar ratio of the zeolite precursor was about 20). 10 cc of the aqueous solution containing the composite sol was added to the mixed solution of the surfactant and the organic solvent, and the mixture was stirred at 50 ° C. with a magnetic stirrer to prepare a microemulsion. This microemulsion solution is stirred well for 1 hour, transferred to an autoclave with an internal volume of 100 cc, and hydrothermal synthesis is carried out at 100 ° C, 120 ° C, and 140 ° C under stirring to produce mordenite-type zeolite particles. Went.

  Washing, drying, and firing after hydrothermal synthesis were in accordance with Example 1. Thereafter, the obtained particles were dispersed in a 1 mol / l ammonium nitrate aqueous solution, subjected to ion exchange treatment, sodium ions in the zeolite were removed, dried again at 80 ° C., and calcined at 500 ° C.

  The particles thus obtained were mordenite-type zeolite particles having a uniform particle size of nanoscale and solid acidity. Table 6 shows the characteristics (calculated in the same manner as in Example 1) of these Y-type zeolite particles.

Comparative Example 1
(Manufacture of silicalite (MFI type zeolite) particles)
To a beaker having an internal volume of 100 ml, 35 cc of 50 cc of ion-exchanged water and 10% strength tetrapropylammonium hydroxide aqueous solution were added. 15 g of ethyl silicate is added to the solution, and the mixture is stirred at room temperature for 24 hours to age a zeolite precursor that is a constituent of Si zeolite, and a composite sol with tetrapropylammonium hydroxide that is a quaternary alkylamine hydroxide. Was generated. 80 cc of the aqueous solution containing this composite sol was stirred well at 50 ° C. for 1 hour, transferred to an autoclave with an internal volume of 100 cc, and each of 80 ° C., 100 ° C., 120 ° C., 140 ° C., and 160 ° C. under stirring. At temperature, hydrothermal synthesis was performed to produce MFI type silicalite.

  After hydrothermal synthesis, the produced precipitate was immediately recovered from the mother liquor, and the obtained precipitate was washed with water three times. This precipitate was dried at 80 ° C. for 12 hours, and then calcined at 500 ° C. for 5 hours under air flow. As a result, about 1.0 g of MFI type silicalite was obtained. The particles thus obtained have a large average particle size of about 1500 nm (calculated in the same manner as in Example 1), and only particles having a larger particle size than the MFI zeolite obtained in the above Examples can be obtained. It was.

  The zeolite of the present invention is a nano-size zeolite having a large particle size with a larger number of particles in the vicinity of the average particle size, and is therefore useful as a catalyst, an adsorbent, an ion exchanger, an optical material, a film formation, and the like. is there.

Scanning electron micrograph of MFI type silicalite synthesized at 140 ° C. in Example 3

Claims (4)

The average particle diameter D made of crystalline silica or crystalline aluminosilicate is 50 nm to 200 nm, and more than 80% of the particles are distributed in the range of 0.9D to 1.1D, and the crystal structure is MFI structure, FAU structure or MOR Nanocrystalline zeolite particles that are structured . The nanocrystalline zeolite particles according to claim 1, wherein the crystal structure is an MFI structure. To a mixed solution of a surfactant and an organic solvent, an aqueous solution containing a composite sol composed of Si or Si and Al zeolite constituents and a quaternary alkylamine hydroxide is added, and an aqueous phase, an oil phase, and a surfactant are added. The method for producing nanocrystalline zeolite particles according to claim 1 or 2, wherein the zeolite particles are formed by hydrothermal treatment at 50 ° C to 200 ° C. The method for producing nanocrystalline zeolite particles according to claim 3, wherein the surfactant is a nonionic surfactant.